Benzyl 2-acetamido-2-deoxy-3-
O-methyl-α-d-glucopyranoside (
3) was obtained by deacetalation of its 4,6-
O-benzylidene derivative (
2). Compound
2 was prepared by methylation of benzyl 2-acetamido-4,6-
O-benzylidene-2-deoxy-α-d-glucopyranoside with methyl iodide-silver oxide in
N,N-dimethylformamide. Diol
3 was selectively benzoylated and
p-toluenesulfonylated, to give the 6-benzoic and 6-
p-toluenesulfonic esters (
4 and
5, respectively). Displacement of the sulfonyl group of
5 with sodium benzoxide in benzyl alcohol afforded the 6-
O-benzyl derivative (
6). Glycosylation of
4 with 2,3,4,6-tetra-
O-acetyl-α-d-galactopyranosyl bromide (
7) in dichloromethane, in the presence of 1,1,3,3-tetramethylurea, furnished the disaccharide derivative
8. Similar glycosylation of compound
6 with bromide
7 gave the disaccharide derivative
10.
O-Deacetylation of
8 and
10 afforded disaccharides
9 and
11. The structure of compound
9 was established by
13C-n.m.r. spectroscopy. Hydrogenolysis of the benzyl groups of
11 furnished the disaccharide 2-acetamido-2-deoxy-4-
O-β-d-galactopyranosyl-3-
O-methyl-d-glucopyranose (
N-acetyl-3-
O-methyllactosamine).
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